262 DELIBERATE INTRODUCTION OF NEW ANIMALS 



recommenced its evil work: in Asia it has spread from Japan 

 to Ceylon ; it has reached Australia and the islands of the 

 Pacific; in America it has made its home from Canada, the 

 United States and isles of the West Indies to Brazil and 

 Argentina. In Europe it is mainly confined to the southern 

 countries, especially France and Italy, though in 1898 it 

 made an appearance in England, where it was speedily sup- 

 pressed owing to the energetic action of Professor R. New- 

 stead. In infected countries many methods have been tried 

 to check the plague, but the most efficient is undoubtedly 

 that of a counter-pest, parasitic upon the Scale, which has 

 been recently bred by A. Berlese from material in Italy. In 

 the efficiency of this tiny Hymenopterous insect, belonging 

 to the family of the small active Chalcids, and known after 

 its discoverer as Prospaltella berlesei, great faith has been 

 placed, for in Italy large trees, entirely covered with Mulberry 

 Scales within the bodies of which the larvae of Prospaltella 

 live and feed, have been completely cleared in eighteen 

 months. The efficiency of the parasite is increased by its 

 fertility, for Prospaltella is said to have in a year four or 

 five generations of females, each of which lays about 100 

 eggs so that the potential progeny of one individual at 

 the end of a season lies between one hundred millions and 

 ten thousand millions. The Chalcid is distributed in in- 

 fected districts on mulberry twigs bearing Scales parasitized 

 by the counter-pest, and these twigs are attached to the 

 branches of scaly trees. 



It was little wonder, then, that Uruguay, troubled with 

 the Mulberry Scale, should apply in 1913 to Italy for a supply 

 of her Chalcids. These were sent; they survived and 

 thrived, spread and colonized the land. Thence in 1914 

 some of the Chalcids were transported to the Argentine, 

 where Mulberry Scale had made its appearance some ten 

 years before. The extent of man's influence in adding 

 new species to a fauna for utilitarian ends may be judged 

 from the statistics of the National Commission nominated 

 by the Argentine Ministry of Agriculture for the express 

 purpose of establishing Prospaltella berlesei. From June 

 to mid-September 1916, 4650 fruit-growers in Argentina 

 applied for the parasitized twigs, and received in all over 

 530,000 twigs, each of which bore many individuals of the 



